Process for the production of sintered products



A ril 4, 1939; H. -WENDEBORN 2,152,713

PROCESS FOR THE PRODUCTION OF SINTERED PRODUCTS Original Filed May 13,1937 3 Sheets-Sheet l ATTORNEY April 4, 1939. H. WENDEBORN 2,152,718

PROCESS FOR THE PRODUCTION OF SINTERED PRODUCTS Original Filed May 15,1937 3 Sheets-Sheet 2 QOOOOOO-DOOOOQ AO0OOOQG He/mul Vl endearw- QQ NMApril 4, 1939. H. WENDEBORN PROCESS FOR THE PRODUCTION OF SINTEREDPRODUCTS Original Filed May is, 1937 5 Sheets-Sheet 5 [/7 Van 2' 1";H/niuf P1 6178 6 0112 A 2 for/Jay Patented Apr. 4, 1939 PATENT OFFlCPROCESS FOR THE PRODUCTION OF SINTERED PRODUCTS Helmut Wendeborn,

Gernfa ny, assignor to American Lurgi Corpora- Frankfort-on-the-Main,

tion, New York, N. Y., a corporation of New York Original applicationMay 13, 1937, Serial No.

142,375. Divided and this application December 2'7, 1937, Serial May 20,1936 9 Claims.

This application is a. division from my application, S. N. 142,375,dated May 13, 1937.

This invention relates to a process for the production of a sinteredproduct.

The first practical solution of the problem of either manufacturingcement by sintering on blast grates-especially induced-draught gratesthe finely ground originating materials, subsequently transformed into agranular or crumbly condition, or of treating other endothermic finematerials likewise subsequent to their transforming into a granular orcrumbly condition, consisted in subjecting'a mixture of the originatingmaterials and the sinter returns, to a sintering operation. In thisprocess it was also important to render the charge on the blast roastinggrate sufiiciently pervious to air by the granulation. To this end,according to one known process, the raw material was strewn overmoistened cores of sinter returns, while the latter were being rolled ina drum. In this manner the cores become coated with thin shells ofcement raw meal to'which a part or the whole of the requisite amount offuel may have previously been added. For this process considerableamounts of sinter returns are required ranging between 100 and 200% ofthe weight of the originating materials.

The invention contemplates a special preparation of the originatingmaterials serving for the manufacture of cement or the like with a viewto adapting them to the sintering operation on the grate, particularlyan induced-draught grate, thus rendering the addition of sinter returnswholly or for its greater part superfluous.

According to the present invention the ground originating materials aredistributed in a liquid medium and this mixture is treated with gas inthe presence of moisture. By this means the originating materials aretransformed into a porous and granulated condition and may be subjectedto a sinter operation on the blast grate without admixture of sinterreturns or adding only a small amount thereof, say 10-30% by weight.

Furthermore, it is an object of the invention to prepare for themanufacture of cement a mixture of the finely ground originatingmaterials with a liquid medium, in which mixture the finely dividedoriginating materials are in suspension to transform the finely groundoriginating materials of the mixture into crumbs and to sinter thesecrumbs mixed with fuel on a sintering grate by burning out the fuel bymeans of air sucked through the charge. 7

If sinter returns are added to the crumbs when No. 181,816. In Germanycharging them onto a. sintering grate, one uses the fines produced whenremoving the sintered product from the blast grate and crushing the.clinker to the desired size or when screening the clinker. It is,according to the invention, not necessary to use a larger amount ofsinter returns for cement burning on the blast grate than obtained bythis method.

Seeing that, according to the invention, the addition of sinter returnscan wholly or partly be dispensed with, the throughput efficiency of theblast grate is considerably increased. At the same time the fuelconsumption referred to an equal amount of finished product, is notablyreduced and it is no longer necessary to crush a portion of theproduction of clinker as hitherto was required so as to obtainsufficiently large amounts of sinter returns.

The process according to the invention ensures a transformation of theoriginating materials into granules'or crumbs containing larger orsmaller inclusions of air and exhibiting, for example, a shell-like orspongy texture, or which have the form of hollow balls or fractionsthereof.

This special texture is the reason why the charge prepared in accordancewith the invention shows a particularly favourable behaviour whensintered on the blast grate.

To the water, the solution, the liquid mixture, the gas or steam usedfor the atomization of the material there may also be added substancessuch as soap, tar, fatty acids, 011 and the like, which are adapted toimpart suflicient tenacity and strength to the texture of the granulesor crumbs.

The mixture of finely ground originating materials with a liquid mediumaccording to the invention is obtained by starting from a mixture of theoriginating materials with the liquid me: dium, in which the originatingmaterials are suspended. This mixture is brought into intimate contactwith the gaseous medium which simultaneously has the task of evaporatingthe liquid medium to such an extent that the originating materials aretransformed into a crumbly condition; hence the gaseous medium is usedin a heated condition.

If the material so prepared, in admixture with fuel, which may be addedbefore, during or after the transformation of" the originating materialsinto granular condition, is disposed as a layer with the ordinary depthof about -30 for instance cm. on a similar grate and ignited on thesurface, it will burn to uniformly calcined clinker free fromimperfectly burned portions.

Cement raw meal is, for example, first mixed with water, thus obtaininga suspension of raw meal in water. Or an already existing suspension,for instance cement raw slurry, is used. The suspension is placed in avessel, the bottom of which is provided witha very large number of smallopenings. Below the bottom of the vesse'l is a wind chest into whichexhaust hot gases, hot air or other hot gaseous medium (such assuperheated steam) are introduced under pressure. The gases flow throughthe openings in the bottom ofsaid vessel and bubble up through theslurry, thereby producing a powerful drying eflect. At thesame time, thewhole of the slurry is caused to froth up and become permeated withminute air bubbles. The slurry gradually 'consolidates, through theevaporation of water, and assumes a specific jmoist earth-likecondition, which can be dried, to a further slight extent, if necessary.The resulting crumbs of raw cement slurry are extremely suitable fordirect burning to cement clinker on the sintering machine.

- A further advantage of this process. consists in the employment of theexhaust gases from the sintering apparatus for drying the slurry andproducing the spongy texture.

In the drawings:

Fig. l illustrata a vertical sectional view of an apparatus for carryingthe process of the invention into practice;

Fig. 2 depicts a similar view of a modified apparatus employed incarrying out the process of the invention; 1

Fig. 3 shows a cross sectional view taken on line III-III of Fig. 2;

Fig. 4 is an enlarged sectional and fragmentary view of one of thenozzles shown in Figs. 2 and 3 and of the protecting hood associatedtherewith;

Fig. 5 illustrates a vertical sectional view of a modified apparatus forcarrying out the process of the invention;

Fig. 6 depicts a side elevational view of a vibrating table employed inthe process of the invention; and

Fig. '7 shows a rotary drum mounted in an inclined position, employed inthe process of the invention for consolidating the crumbs of the treatedmaterial.

According to Figure 1 a vessel I contains a suspension of the finelydivided originating materials in a liquid medium, e. g. cement rawslurry. Through the pipe 2 the slurry proceeds to the bottom 3 which isprovided with nozzles 8 and the tipping vessel 5. The fan 9 forces thehot gases into the wind'box 4'. These gases after 1 having flown throughthe nozzles in the bottom 3 bubble up through the slurry'fed to the box6 from vessel I, thereby drying the slurry to the desired degree whileat the same time the slurry which the slurry is continuously fed to arotary tube through a pipe 23. Inner jacket 30 of the rotary tube isprovided with a large number of nozzles 33 to which the dryinggases arefed through pipes 29 and an outer jacket 3| surrounding the 24 supplying.the drying gases.

obstructing the passage of drying gases through the nozzle. Referencecharacter 32 denotes the conventional driving mechanism of the rotarytube. For the introduction of the gases into the .rotary tube, astationary distributing head 23 is provided which is connected with afan or blower A pair of sealing or packing members 36 are mounted onstationary distributing head 23 and provide a substantially gas tightseal with distributing pipes 29 rotating with inner and outer jackets30, 3|. As shown in Fig. 3, the space formed between jackets 30 and 3|is subdivided by means of partition walls 31 into a plurality ofcompartments, each compartment being connected with a distributing pipe29. A packing plate or member 38 is mounted at the end of each partitionwall 31, in order to provide a substantially gas tight seal between theadjoining compartments. Stationary dis-' with the stationarydistributing head 23, the one which happens to be in the lowestposition. Therefore, as indicated by the arrows in Fig. 2, the dryinggases supplied by blower 24 are caused to flow only through that portionof inner jacket 30 which is covered by the charge. The treated materialis continuously discharged from the inner jacket 30 into a reservoir orvessel 25 and from this vessel it is carried by means of a. vibrating orshaking conveyer 26 to the sintering plant. Vessel 25 is provided withan outlet opening 39 for the waste gases. Preferably, heating means inthe form of a plurality of gas jets 40 are provided underneath outerjacket 3| of the rotary tube. Heating means 40 heat outer jacket 3| ofthe rotary tube and the gases entering from tube 29 to a hightemperature so that the slurry to be dried and the foaming additionscontained therein are decomposed.

The rotary tube having jackets 30 and 3| may be so constructed thatafter the treatment the charge is continuously discharged or the tubemay be tipped after the treatment is finished, in order to discharge thetreated material. In view of the fact that the tipping arrangement is ofconventional character and does not form part of the invention, itsillustration has been omitted from the drawings. The depth of the layerof slurry in the rotary tube should, preferably, not exceed 10 to 20 cm.The volume of the slurry is increased to many times its original valueby the foaming process at the commencement of drying.

It has also been foundadvisable to carry out this method foaming processfrom the very beginningin a rotary drum, the whole or part of the shellof the drum 30 being provided with nozzles 33 or other suitableopenings, through which the air, exhaust gases or the like, can beintroduced and passed through the slurry while the drum 30 is beingrotated.

Finally, one can also use a suspension of the priginating materials ofviscous, pulpy or pasty condition inflating it by rapid heating or thelike, for example, by heating the outer jacket 3| of the rotary tube bymeans of gas jets 40 whereby the gaseous medium is heated up to such adegree that the foaming substances added to the slurry are decomposed orare inflated by heat.

The invention also enables cement raw slurry to be dried by exhaustgases, in a simple manner, so that the burning process does not requireany greater amount of heat than in burning dry raw material. Anapparatus of this type is illustrated in Fig. in which referencecharacter 4'! denotes a sintering apparatus having a wind box 48 and ahopper 46 through which material to be sintered is fed to the apparatus.Wind box 48 is connected to a blower 50 by means of a conduit 49, theblower in turn being connected by means of a conduit 5| to thedistributing head 23 which distributes the hot exhaust gases between thevarious sections of the rotary tube. In view of the fact that the rotarytube illustrated in the upper portion of Fig. 5 is identical with theone shown in Fig. 2 and identical reference characters have beenemployed to denote corresponding parts, no detailed descriptidn of therotary tube and of its operation will be necessary. The raw cementslurry, after it has been dried in the rotary tube, isslightly'consolidated in a bladed conveyor 45 and is charged onto therotary hearth 41 where it is subjected to a final burning treatment.

Fig. 6 illustrates a vibrating table which may be employed in theapparatus shown in Fig.5 instead of the bladed worm or conveyor 45.Vibrat-- ing table 39a is resiliently mounted on springs-42 and ismaintained in vibrations by means of a rotary shaft 40 and an eccentric4|. Fig. Hiepicts a rotary drum 43 mounted in a slightly inclinedposition and having a feed hopper 44. The vibrating table or the rotarydrum may be employed with equal or similar results for slightlyconsolidating the crumbs produced from the raw slurry of finely groundraw materials, as those skilled in the art will readily understand.

I claim:

1. The process of producing cement which comprises forcing a hot finelydistributed gas stream through a raw slurry of finely ground rawmaterial in such amounts as to transform said slurry into porous crumbs,admixing fuel to said crumbs, charging said crumbs in admixture withfuel onto a grate, and forcing air through said charge on said grate tocause burning of said fuel and sintering of said crumbs.

2. The process of producing cement which comprises mixing a raw slurryof finely ground raw materials with substances selected from the groupconsisting of fatty and tarry liquids, acids and oils, to consolidatethe texture thereof, forcing a hot finely distributed gas stream throughsaid raw slurry to transform the same into porous crumbs, admixing fuelto said crumbs, chargingsaid crumbs in admixture with fuel onto a grate,and forcing air through said charge on said grate to cause burning ofsaid fuel and sintering of said crumbs.

to slightly consolidate the same, admixing fuel to 10 said crumbs,charging said crumbs in admixture with fuel onto a grate, and forcingair through said charge to cause burning of said fuel and sintering ofsaid crumbs.

4. The process of producing cement which comprises forcing a hot finelydistributed gas stream through a raw slurry of finely groundrawmaterials in such amounts as to transform said slurry into porouscrumbs, slightly consolidating said crumbs in a bladed worm, admixingfuel to said crumbs,charging said crumbs in admixture with. fuel onto agrate, and forcing air through said charge to cause burning of said fueland sintering of said crumbs.

5. The process as claimed in claim ,3 in which,

the crumbs are slightly consolidated by shaking conveyers.

6. The process as claimed in'claim 3 in which the crumbs areconsolidated by vibrating means.

7. The process as claimed in claim 3 in which the crumbs areconsolidated in a rotary drum; 8; The process of producingcement whichcomprises adding foaming substances to a. raw slurry of finely groundraw material, forcing a h'ot finely distributed gas stream through saidraw slurry a to transform the same into porous bodies including porouscrumbs, bubbles, shells and the like, admixing fuel .to said bodies,charging said porous bodies in admixture with fuel onto a grate,

and forcing air through said charge to cause 40 burning of said fuel-andsintering of said porous bodies.

9. The process of producing cement which comprises adding foamingsubstances to a raw slurry of finely ground raw materials, forcing a hotfinely distributed gas stream through said raw slurry to 1 transform thesame into porous bodies including porous crumbs, bubbles, shells, andthe like, rapidly heating said porous bodies to inflate the same,

admixing fuel to said bodies, charging said bodies in admixture withfuel onto a grate, and forcing air through said charge to cause burningof said fuel and sintering of said porous bodies.

hm UT WINDBORN.

